It is well known in the industry that watercraft with a multi-hull design provide better seakeeping in moderate-to-high wave conditions than mono-hull vessels. Multi-hull ships can be designed to experience only one-half to one-fifth of the heave, pitch, and roll motions of a monohull vessel of equal displacement in seas driven by wind speeds above 20 knots.
An additional benefit of multi-hull designs is that they can travel at faster speeds than a mono-hull design. The wave penetrating features of a multi-hull design allow the watercraft to also maintain course and speed during sea conditions that would otherwise defeat a mono-hull's ability to maintain the same course and speed.
As claimed and disclosed in the present inventor's U.S. Pat. Nos. 5,549,066 and 6,883,450 a multi-hull, with each hull having a bow and stern sections that are essentially symmetrical and have wave penetrating features is featured. The bow and stem sections are formed from more than three, preferably five triangular surfaces meeting at meet a common point.
Other various hull designs have been introduced. In an article titled “Variable Draft Broadens SWATH Horizons” in the April 1994 issue of Proceedings, improvements are made to the design known as Small Waterplane Area Twin-Hull (SWATH) ships. The SWATH design for this particular boat utilizes struts that are aligned on the centerline of the lower hull. The lower hull's rectangular cross sections enhance seakeeping at deeper drafts and give best propulsion at transit depths. The center bow provides a cushion against slamming and affords convenient overboard access for handling equipment. Rectangular hull forms supportive of the SWATH design are less expensive to fabricate and outfit than conventional hull designs.
The U.S. Navy test vessel, Sea Shadow, was built to test several aspects of maintaining stealthiness at sea, including low radar visibility, quietness to sonar sensors and minimizing wake. An article titled “The Secret Ship” in the October 1993 issue of Popular Science discussed the unclassified parameters of this vessel. Above the waterline, the Sea Shadow's resemblance is similar to that of the U.S. Air Force F-117A stealth fighter. From the waterline down, the exact details are classified, but the ship's underwater shape is essentially a SWATH design. A pair of submerged pontoons gives the Sea Shadow its buoyancy. Running beneath the water's choppy surface layer, these pontoons cause far less of the seasickness-inspiring vertical motion inherent in traditional mono-hull designs.
Another unique design is the trimaran hydrofoil designed and built by Greg Ketterman, as discussed in an article titled, “World's Fastest Sailboat,” in the January 1991 issue of Popular Science. The hydrofoil is a two-mast, triple-hull design that utilizes sensors forward of the outer hulls that hug the water's undulating surface, constantly adjusting the pitch of the hulls and main foils to maintain stability and minimize drag. Foot pedals control the rudder. This design is primarily for sail boats that want to maximize speed through the waters. However, this design is not suitable for large boats and lacks a propulsion system often desired in larger boats.
Ocean Waves, even in relatively calm seas, have amplitudes and lateral modulations. In stormy seas, those amplitudes and modulations often tear multi-hull ships apart. The current propulsion systems for large multi-hull ships lack a mechanism to cope with the up and down movement of the waves, and also lack structure to protect the multi-hull ship from being ripped apart.
Recently, wave piercing designs have been developed which have shown great promise. As disclosed in an article entitled, “Wave Piercers and Fast Cats”, written by Richard Akers and published in December/January, 2002 issue of Professional Boatbuilder, multiple narrow hulls enable the use of substantially less horsepower to propel the craft than a vessel having similar displacement but with wider multiple hulls or a mono-hull.
The U.S. Navy, among others, is also interested in having speed vessels, some of which have flat decks for use as equipment carrying ships. The desire for higher speed ships as well as ships being more difficult to see on radar is near the top of the Navy's wish list. As example, discussed in the U.S Navy Proceedings, January, 2003, the need for a combat littoral ship which is lethal, agile, survivable and versatile is critical if the U.S. is to maintain naval supremacy. However, a catamaran hull design is limited and it lacks the stealth capability and is not self-righting if rolled over.
All of the above are particularly important when attempting to design racing boats. The typical high speed racing hydroplanes are known to have problems of having the bow lifting up due to relative small action which causes the hull to porpoise. The bow lifting causes the stern to dig in further, the engines keep driving the craft forward, and, finally, the boat can become airborne, eventually flipping over on its back. Such crashes frequently cause operators severe injuries and even can be fatal.
A typical mono-hull high performance boat used for offshore racing is about 42 feet long and has a beam of 8 feet. The length and beam are limited to what can be legally hauled over the highway without incurring special wide load permits. The typical boat is a deep V design manufactured from fiberglass or sometimes more exotic materials such as Kevlar. Multiple engines are customarily large block car or truck engines connected to out drives. The cockpit is usually open with at least four seats and harnesses to keep the passengers and operator from being ejected when the boat “porpoises” due to encountering waves.
This type of racing is limited to those having extraordinary amounts of money as the cost of the speedboat, maintenance and fuel is well beyond most people's means. These boats attain speeds of over 170 mph. This type of racing is very dangerous and requires a craft that is able to withstand the enormous pressures and strains that are being placed on the hull, its fittings and the engines. Money is usually of little consequence to those who attain to win one of these offshore races.
Therefore, a multi-hull design for a large boat that protects the speedboat from being ripped apart by the changing amplitudes and modulations of the ocean, is faster than competing craft, can be transported on the nation's highways using a low boy trailer without special permits and a propulsion system that provides a means for optimizing the ship's speed through varying sea conditions ship is desired in the art.